In recent years, radiation-emitting devices have been widely used for an increasing number of purposes. All of such radiation-emitting devices include an envelope, an enclosed gas, and a pair of electrodes between which an electron flow is established.
Those skilled in the art are familiar with the operation of such devices, and it is not necessary to recite here operational details which have little bearing on this invention. It suffices to note that when an electron flow is established between electrodes, electrons strike certain atoms, such as mercury, and raise the energy level of another electron in the atom. When this electron (e.g., in the mercury atom) returns to its normal state, a ray of ultraviolet energy is released.
Such emissions are used for various purposes, including: lighting, by exciting phosphors as in fluorescent lamps; treating flowing liquids, such as water; and initiating laser discharges. One application to which this invention is particularly relevant is the treatment of flowing liquids.
This invention deals primarily with structural aspects of such radiation-emitting devices.
Many variations have been made in radiation-emitting apparatus, including variations in the gases, in gas pressures, in various devices for creating conditions necessary for radiation discharge, and in mounting structures for such devices, to name ust a few. Some variations have been made in the size and shape of gas-containing envelopes.
The dominant shape of radiation-emitting envelopes has been cylindrical. Variations have dealt primarily with such things as doubling back the envelope to increase the length of the electron path for a single electron discharge and deforming portions of the envelope to create a more tortuous electron path for various purposes. In most cases, however, the common cylindrical envelope shape has been used in one way or another. Examples of the prior art include the following U.S. Pat. Nos.
4,468,590 PA1 2,596,697 PA1 3,471,630 PA1 3,226,590 PA1 3,253,176 PA1 2,205,000 PA1 2,213,245 PA1 2,862,337 PA1 2,915,664 PA1 2,916,645 PA1 3,295,003 PA1 3,303,042 PA1 4,454,448 PA1 4,514,662 PA1 3,875,530 PA1 4,071,798 PA1 1,794,343 PA1 2,267,118 PA1 2,482,421 PA1 4,195,249 PA1 4,234,817 PA1 4,272,702 PA1 4,320,324 PA1 3,121,183 PA1 3,560,786 PA1 3,988,633 PA1 4,099,090 PA1 4,196,374 PA1 4,260,931 PA1 4,281,271 PA1 4,445,069 PA1 2,674,697 PA1 2,935,611 PA1 3,527,940 PA1 3,566,105 PA1 3,837,800 PA1 4,008,045 PA1 4,017,734 PA1 4,048,504 PA1 4,101,777 PA1 4,141,686 PA1 4,336,223 PA1 4,482,809 PA1 4,535,247
There are a number of problems and disadvantages with radiation-emitting devices of the prior art. Some of these will be briefly mentioned.
In many devices of the prior art, portions of the envelope volume have a sparsity of active fluorescing sites. And there is too great a degree of radiation reabsorption by the gas within envelopes of the prior art.
Prior art devices have some disadvantages relating to a failure to efficiently apply emitted radiation on a material to be irradiated, particularly flowable materials. Regions of flowing material are often too remote from the radiation source to be effectively treated. The law of inverse squares, in many structures for fluid treatment by radiation emitted outwardly through a cylindrical wall, creates areas of unacceptable exposure. And, passage of a fluid to be treated through an array of cylindrical radiation-emitting tubes often creates turbulence which is a negative factor on irradiation effectiveness.
The envelope structures of the prior art have other problems which are related to envelope materials. The standard cylindrical envelope, in order to use high-pressure gases as is often desirable to increase radiation output, require quartz envelope cylinders which are extremely thick, in order to provide sufficient strength. That is because quartz and similar radiation-transmissive materials, while they function well under compression (i. e., pressure applied to a convex surface) do not withstand tension (i. e., pressure applied to a concave surface) very well.
Finally, envelopes of prior art radiation-emitting devices are not easily adaptable to meet the varying requirements of important radiation-emitting applications. There is a need for envelopes and envelope concepts which can be adapted and engineered to better serve important practical needs.
There is a need for improved envelope devices which can increase efficiency of radiation emission, and for improved devices maximizing the number of active fluorescing sites within the envelope. More specifically, a need exists for an improved radiation-emitting envelope which reduces the reabsorption of radiation occurring within the envelope volume. There is a need for an envelope which decreases the path length that radiation must travel before leaving the envelope, while at the same time directing the radiation more specifically toward an exterior target than is the case with the standard cylindrical envelope.
Another significant need is to provide envelope structures which are more suitable for certain specific purposes than the current cylindrical envelopes. There is a need for radiation-emitting envelopes which apply radiation more effectively to materials to be irradiated, particularly fluid streams, as in water purification. There is a need for envelopes which can minimize the turbulence in a stream of fluid passing them for irradiation.
There is a need for envelope structures which can contain high-pressure gas and yet not require thick and expensive radiation-transmissive members. Also there is a need for envelopes structures which can be made using materials which may be formed as required to achieve various purposes. There is a need for a radiation-emitting envelope which can eliminate the need for a separate holder.
There is a need for improved radiation-emitting envelopes which lend themselves to easy fabrication and maintenance, are simple to install and efficient in operation.